Any refinery process water, petroleum chemical waste water, ballast waste water, river water, underground feed water, ethylene quench waste water, oil-in-water waste emulsions from oil recovery fields, and the like are contaminated waters requiring difficult chemical treatment and clarification. These aqueous systems are also found in steam cylinder dispersions in which small amounts of oils which are used for lubrication may be found in the steam of engines and pumps; emulsions and other dispersions containing polystyrene and styrenes-in-water frequently found in synthetic rubber manufacturing facilities; emulsions and other dispersions obtained during clay pipe manufacture using steam initiated processes; oil-in-water emulsions or dispersions which are found in coolant water devices and in gasoline absorption facilities; emulsions and dispersions containing wax-type products which are encountered in oil refinery dewaxing procedures; "fluxoil" emulsions and dispersions occurring in condensate steam resulting in dehydrogenation of butylene during catalytic procedures to produce butadiene; emulsions and dispersions obtained during procedures for making butadiene from naphtha by means of standard "cracking" procedures in gas generators; emulsions and dispersions in latex-in-water formed in copolymerization procedures for butadiene and styrene derivatives.
Such dispersions and emulsions are also problems in synthetic resin paint and pigment manufacturing processes, as well as in food processing of derivatives of pasteurized additives. In each of these processes, as well as in the equipment which is used during steps in the various procedures, oil-in-water emulsions or dispersions of a non-aqueous phase are inherently formed as a by-product of the particular given operation. The disposal of the produced waste water becomes a problem which is compounded by the presence of the oil-in-water emulsions, or dispersions containing a non-aqueous discontinuous phase. Often, extreme difficulties are presented in the treatment and clarification processes employed. If one were to successfully treat these kinds of waste waters which contain oily waste matter as well as dispersed solid matter of an organic or inorganic nature, one could advance the art of treating and clarifying contaminated waters of this type.
The present invention is directed to the clarification of such aqueous systems, so that the resultant stream of the aqueous system contains essentially two separate phases; an oil- or hydrocarbon-based phase, or non-aqueous phase, and an essentially aqueous phase, with the resultant aqueous phase being clarified without the production of a problematic floc. Clarification is accomplished with water clarifiers which are compounds which, when added to produced water containing oil, form "flocs." The dispersed oil and solid particulates absorb on the floc and thereby are removed from the water when the floc is skimmed off the surface of the treated water. The treated aqueous system can then pass certain industrial and/or governmental water clarity tests or specifications and be discharged. The dispersed oil and/or solid particulates may also be recovered.
The aqueous systems contemplated in this invention will contain water in various forms, such as tap water, brines or seawater (in the case of aqueous systems involved in the drilling, completion, workover or production of subterranean oil or gas wells), and the like.
In any oil-in-water emulsion, the amount of oil in the water or aqueous phase, or in the case of a dispersion of non-aqueous phase, the amount of such non-dispersed phase will vary considerably depending on the industrial application. In the case of emulsions which are frequently found in the oil field and in applications of well completion operations, the oil-in-water emulsion will contain a crude oil content varying from a few parts per million to about 20%, by volume or even higher.
In treating such emulsified or dispersed aqueous systems for disposal or other uses or recycling, it is necessary to break the emulsified oil-in-water or resolve the dispersion such that the oil phase, or the non-aqueous dispersed phase and the water phase may be separated. The water should be clarified by the demulsification treatment without production of a problematic "floc".
"Floc" is considered to be a by-product of water clarification which may vary in characteristics depending on the composition of the clarifier used to clarify the water. While "floc" may always be expected to be produced as a result of a water clarification treatment procedure, such "floc" should be made to be controllable. A problematic floc may adversely affect operations or clarification systems by means of adherence, plugging and interface problems with manufacturing equipment or production equipment. Floc characteristics can be visually judged by observing a sample of the treated aqueous system. The present invention contemplates water clarification such that the floc which is formed does not cause operational problems in the treatment system by means of adherence, plugging, or interface buildup with equipment being exposed to the aqueous system. An improved floc is one that is easily skimmed and does not build up in the system--essentially, a floc which is easier to handle.
In the past, those skilled in the art have recognized the use of derivatives of certain amines as demulsifiers in water clarification procedures. These derivatives are obtained by reacting amines with carbon disulfide and materials which are sources of alkali metal ions, alkali earth metal ions, ammonium ions and amine ions from other reactants. The preparation of dithiocarbamates has long been known, see for example, U.S. Pat. No. 1,788,632 which describes a process of making these organic sulfur compounds. U.S. Pat. No. 2,457,209 teaches dithiocarbamates as resinous adhesives. Lubricant compositions comprising an additive combination to improve the anti-oxidant and rust-inhibiting properties of these compositions are disclosed in U.S. Pat. No. 3,876,550. European Patent 13,462 B1 describes compositions comprising mixtures of a dithiocarbamic acid derivative and a sulfonium compound such as triphenylsulfonium chloride and suggest they provide effective corrosion inhibition in acid treatment of metal in the presence of a copper complexing agent such as thiourea.
Dithiocarbamates have also been known to be used as separation agents. For example, see U.S. Pat. No. 2,589,209 which mentions that dithiocarbamate-aldehyde condensation polymers may be useful as flotation agents. Typical of such prior art are U.S. Pat. Nos. 4,689,177; 4,826,625; 4,864,075; 4,956,099 and 5,013,451, which teach the use of nitrogen-containing dithiocarbamic acid compositions formed by the reaction of alkoxylated triamines with CS.sub.2 as "reverse" demulsifiers. While certain of the materials disclosed in these patents may or may not be used satisfactorily to demulsify particular aqueous systems, it has been found that not all such materials are satisfactory to clarify water without the production of a resultant problematic floc. U.S. Pat. Nos. 5,013,451 and 5,019,274 teach a different set of dithiocarbamates for water clarification by demulsification and flocculation, respectively, from those mentioned in the '177; '625 and '075 patents. The dithiocarbamates of the '451 and '274 patents are made using non-alkoxylated and alkoxylated amines having linear, branched and cyclic aliphatic carbon chains.
European Patent Application 249,320 describes dithiocarbamates made from alkyl and alkenyl diamines, alkyl and alkenyl triamines and alkyl and alkenyl tetramines. The application states that these compositions are useful as ferrous iron sequestrants in acidic solutions containing high percentages of acid, and with methods of use thereof as aids in reducing asphaltene precipitation in asphaltenic reservoirs treated with a solution of strong acid.
U.S. Pat. Nos. 4,855,060 and 5,006,274 notes that if bis(hexamethylene)triamine (BHMT) is reacted in an approximate stoichiometric ratio of primary amine with carbon disulfide, that the resultant product can be used to successfully break the emulsion and clarify the water, without the production of a problematic floc. In U.S. Pat. Nos. 4,855,060 and 5,006,274, these problematic flocs were termed "uncontrollable" and it will be understood that these terms refer to the same kinds of undesirable flocs. The commercial product related to the material of this patent is marketed by Baker Performance chemicals, Inc. as MAGNACLEAR.RTM. W213 water clarifier, referred to herein as W213. MAGNACLEAR.RTM. W213 is a trademark for water clarifier products made by Baker Performance Chemicals, Inc.
International application WO 89/10956 describes quaternary ammonium dithiocarbamate compounds and methods of preparing the same by mixing in water a quaternary ammonium compound and a dithiocarbamate salt or a bis-dithiocarbamate salt and recovering the quaternary ammonium dithiocarbamate compound from the organic layer formed thereby. The compositions employing such compounds are said to be primarily useful as surfactants and biocides and also in water treatment in oil drilling or recovery operations, in fuel, cutting fluids and in the flotation of heavy metal ores in mineral beneficiation. Dithiocarbamates made from bis-hexamethylenetriamine were found to be useful as ore flotation agents in Canadian Patent 771,181.
Indeed, dithiocarbamates have been known as ore flotation agents for some time; see, for example, A. M. Gaudin, Flotation, McGraw-Hill, New York, 1957, pp. 182-183 and 209-211. The separation of heavy metal ions from aqueous solutions using dithiocarbamates is also recognized by T. Kitson in "The Dithiocarbamates --Interesting, Versatile and Neglected,", Education in Chemistry, March, 1985, pp. 43-45. A di-methyl dithiocarbamate is taught together with other compounds to assist in solid-liquid separation of copper plating wastewater according to Chemical Abstracts 104(86):23816a. Similarly, the treatment of wastewater containing heavy metal complexes, such as those of copper, iron, zinc or nickel, may be accomplished using dithiocarbamate or other materials as described in Chemical Abstracts 112(90):41931d. Dithiocarbamates are listed as collectors in ore flotation by F. J. Kenney in an article "Use of Surfactants in Mineral Flotation" which appeared in Industrial Applications of Surfactants, D. R. Karsa, Ed., Royal Society of Chemistry, Cambridge, England, 1990, p. 369-370.
Epoxy modified materials have also found uses in separation procedures. For example, U.S. Pat. No. 3,753,931 is directed to water soluble, high molecular polyetheramines and their salts, produced by the reaction, in excess, of aliphatic polyamines which contain at least one primary or two secondary amino groups, may contain hydroxyl groups and have molecular weights not greater than 200, with polyepihalogeno-hydrins which contain 3 to 25 halogenomethyl groups. Removal of excess polyamine from the reaction mixture by distillation follows next, reaction of the resulting polyether amine aqueous solution with crosslinking agents to a degree of crosslinking at which a viscosity increase occurs and the reaction mixture remains water soluble, and if desired partial or complete conversion of the free amino groups into their salts by the addition of acids. These polyamines are useful as flocculating and flotation agents and as drainage and retention aids, especially in paper manufacture.
Other such patents are discussed by S. Gutcho in Waste Treatment with Polyelectrolytes and Other Flocculants, Noyes Data, Park Ridge, N.J. 1977, pp. 81-82 (U.S. Pat. No. 3,493,502--"Condensation Product of Methylamine with Epichlorohydrin for Settling of Ore and Mineral Solids"), pp. 96-98 (U.S. Pat. No. 3,741,891--"Ilmenite Digestion Liquor Treated by an Alkyl Quaternary Epihalohydrin-Monoalkylamine Product"). Similarly, a metal scavenger comprising an addition product of a polyamine and an epihalohydrin is described in European Patent 200,143 B1, the addition product containing as a substituent at least one carbodithio group and/or at least one carbodithioate salt group introduced therein by substituting the corresponding number of active hydrogen atoms in the addition product.
On an oil and gas production site, dithiocarbamic salt water clarifiers work in conjunction with gravity settling equipment, flotation devices, filtration equipment and the like by creating a floc with metal ions in the brine. After the oil and grease have absorbed onto the surface of the floc, the floc is separated and returned to crude production. Most prior flocs are "sticky" and adhere to surfaces inside the equipment. After a relatively short period of time, the build-up of floc on the skimmer, walls and in the trough causes the unit to need to be shut down and cleaned. Preferably, the water clarifier provides an "acceptable" floc which does not cause operational problems in the system via adherence, plugging and interface build-up.